reorganize Gemfile+gemspec

Gemfile

@@ -1,9 +1,20 @@
 source "http://rubygems.org"
 
 # Specify your gem's dependencies in guard-puppet.gemspec
-gemspec
+gemspec development_group: :gem_build_tools
 
-require 'rbconfig'
-if RbConfig::CONFIG['host_os'] =~ /linux/
-  gem 'libnotify'
+group :development do
+
+  require 'rbconfig'
+  if RbConfig::CONFIG['host_os'] =~ /linux/
+    gem 'libnotify'
+  end
+end
+
+group :test do
+  gem 'rspec', '~> 2.6.0'
+  gem 'mocha'
+end
+
+group :gem_build_tools do
 end

guard-puppet.gemspec

@@ -20,7 +20,4 @@ Gem::Specification.new do |s|
 
   s.add_dependency 'guard'
   s.add_dependency 'puppet'
-
-  s.add_development_dependency 'rspec', '~> 2.6.0'
-  s.add_development_dependency 'mocha'
 end